Upgrades the database, turns jConnect support for a database on or off, calibrates the database, changes the transaction log and transaction log mirror file names, or forces a mirror server to take ownership of a database.
Syntax 1 - Upgrading components or restoring objectsALTER DATABASE UPGRADE [ PROCEDURE ON ] [ JCONNECT { ON | OFF } ]
Syntax 2 - Performing calibrationALTER DATABASE { CALIBRATE [ SERVER ] | CALIBRATE DBSPACE dbspace-name | CALIBRATE DBSPACE TEMPORARY | CALIBRATE GROUP READ | CALIBRATE PARALLEL READ | RESTORE DEFAULT CALIBRATION }
Syntax 3 - Changing transaction log and transaction log mirror namesALTER DATABASE dbfile ALTER [ TRANSACTION ] LOG { { ON [ log-name ] [ MIRROR mirror-name ] | OFF } [ KEY key ]
Syntax 4 - Changing ownership of a databaseALTER DATABASE { dbname FORCE START | SET PARTNER FAILOVER }
Syntax 5 - Changing checksum settingsALTER DATABASE dbfile CHECKSUM OFF
ParametersPROCEDURE clause Drop and re-create all dbo- and sys-owned procedures in the database.
JCONNECT clause To allow the jConnect JDBC driver access to system catalog information, specify JCONNECT ON. This clause installs the system objects that provide jConnect support. Specify JCONNECT OFF if you want to exclude the jConnect system objects. You can still use JDBC, as long as you do not access system information. JCONNECT is ON by default.
CALIBRATE [ SERVER ] clause Calibrate all dbspaces except for the temporary dbspace. This clause also performs the work done by CALIBRATE PARALLEL READ.
CALIBRATE DBSPACE TEMPORARY clause Calibrate the temporary dbspace.
CALIBRATE GROUP READ clause Perform group read calibration on the temporary dbspace. Writes large work tables to the temporary dbspace and uses different group read sizes to time the reading of the files. If adding space to the temporary table exceeds the limit for the connection, or if the cache is not large enough to allow calibration with the largest memory size, calibration fails and an error message is returned.
CALIBRATE PARALLEL READ clause Calibrate the parallel I/O capabilities of devices for all dbspace files. The CALIBRATE [ SERVER ] clause also performs this calibration.
RESTORE DEFAULT CALIBRATION clause Restore the Disk Transfer Time (DTT) model to the built-in default values that are based on typical hardware and configuration settings.
ALTER [TRANSACTION] LOG clause Change the file name of the transaction log or transaction log mirror file. If MIRROR mirror-name is not specified, the clause sets a file name for a new transaction log. If the database is not currently using a transaction log, it starts using one. If the database is already using a transaction log, it changes to using the new file as its transaction log.
If MIRROR mirror-name is specified, the clause sets a file name for a new transaction log mirror. If the database is not currently using a transaction log mirror, it starts using one. If the database is already using a transaction log mirror, it changes to using the new file as its transaction log mirror.
You can also use this clause to turn off the transaction or transaction log mirror. For example, ALTER DATABASE ALTER LOG OFF.
KEY clause Specify the encryption key to use for the transaction log or transaction log mirror. When using the ALTER [ TRANSACTION ] LOG clause on a strongly encrypted database, you must specify the encryption key.
dbname FORCE START clause Force a database server that is currently acting as the mirror server to take ownership of the database. This clause can be executed from within a procedure or event, and must be executed while connected to the utility database on the mirror server.
SET PARTNER FAILOVER clause Initiate a database mirroring failover from the primary server to the mirror server. This statement must be executed while connected to the database on the primary server, and can be executed from within a procedure or event. When executed, any existing connections to the database are closed, including the connection that executed the statement. If the statement is contained in a procedure or event, other statements that follow it may not be executed.
CHECKSUM clause Disables global checksums for the database. By default, new databases have global checksums enabled, while version 11 and earlier databases do not have global checksums enabled.
Regardless of the setting of this clause, the database server always enables write checksums for databases running on storage devices such as removable drives, and databases running on Windows Mobile to help provide early detection if the database file becomes corrupt. It also calculates checksums for critical pages during validation activities.
For databases that do not have global checksums enabled, you can enable write checksums by using the -wc options.
RemarksSyntax 1 You can use the ALTER DATABASE UPGRADE statement as an alternative to the Upgrade utility to upgrade or update a database. This applies to maintenance releases as well. After executing this statement, you should restart the database. In general, changes in databases between minor versions are limited to additional database options and minor system table and procedure changes. The ALTER DATABASE UPGRADE statement upgrades the system tables to the current version and adds any new database options. If necessary, it also drops and recreates all system procedures. You can force a rebuild of the system procedures by specifying the PROCEDURE ON clause.
An error message is returned if you execute an ALTER DATABASE UPGRADE statement on a database that is currently being mirrored.
You can also use the ALTER DATABASE UPGRADE statement to restore settings and system objects to their original installed state.
Features that require a physical reorganization of the database file are not made available by executing an ALTER DATABASE UPGRADE statement. Such features include index enhancements and changes in data storage. To obtain the benefits of these enhancements, you must unload and reload your database.
It is strongly recommended that you back up your database files before attempting to upgrade your database. If the upgrade process fails, then the partially upgraded database is marked as invalid and is no longer usable. Attempting to start a database after a failed upgrade results in an error indicating that the database file is not valid.
To use the jConnect JDBC driver to access system catalog information, specify JCONNECT ON (the default). If you want to exclude the jConnect system objects, specify JCONNECT OFF. Setting JCONNECT OFF does not remove jConnect support from a database. You can still use JDBC, as long as you do not access system catalog information. If you subsequently download a more recent version of jConnect, you can upgrade the version in the database by (re)executing the ALTER DATABASE UPGRADE JCONNECT ON statement.
Syntax 2 Use Syntax 2 to perform recalibration of the I/O cost model used by the optimizer. This operation updates the Disk Transfer Time (DTT) model, which is a mathematical model of the disk I/O used by the cost model. When you recalibrate the I/O cost model, the database server is unavailable for other use. In addition, it is essential that all other activities on the computer are idle. Recalibrating the database server is an expensive operation and may take some time to complete. It is recommended that you leave the default in place.
When using the CALIBRATE PARALLEL READ clause, parallel calibration is not performed on dbspace files with fewer than 10000 pages. Even though the database server automatically suspends all of its activity during calibration operations, parallel calibration should be done when there are no processes consuming significant resources on the same computer. After calibration, you can retrieve the maximum estimated number of parallel I/O operations allowed on a dbspace file using the IOParallelism extended database property.
To eliminate repetitive, time-consuming recalibration activities when there is a large number of similar hardware installations, you can re-use a calibration by unloading it and then applying it (loading it) into another database using the sa_unload_cost_model and sa_load_cost_model system procedures, respectively.
Syntax 3 You can use the ALTER DATABASE statement to change the transaction log and transaction log mirror names associated with a database file. The database must not be running to make these changes. These changes are the same as those made by the Transaction Log (dblog) utility. You can execute this statement while connected to the utility database or another database, depending on the setting of the -gu option. If you are changing the transaction log or transaction log mirror of an encrypted database, you must specify a key. You cannot stop using the transaction log if the database is using auditing. Once you turn off auditing, you can stop using the transaction log. This syntax is not supported in procedures, triggers, events, or batches.
You can use the BACKUP DATABASE statement to rename the transaction log for a running database. For example:
BACKUP DATABASE DIRECTORY 'directory-name' TRANSACTION LOG ONLY TRANSACTION LOG RENAME; |
Syntax 4 ALTER DATABASE...FORCE START must be executed from the mirror server, not the primary server. Attempting to execute an ALTER DATABASE...FORCE START statement for a database that is not being mirrored or is currently active and owned by this server results in an error. Also, if the primary server is still connected to the mirror server, an error is given.
Syntax 5 This clause can only be used to disable checksums for a database.
PermissionsFor Syntax 1 and 2, you must have DBA authority, and must be the only connection to the database. ALTER DATABASE UPGRADE is not supported on Windows Mobile.
For Syntax 3, you must have file permissions on the directories where the transaction log is located, and the database must not be running.
For Syntax 4, you must have the permissions specified by the -gk server option.
For Syntax 5, you must have DBA authority.
Side effectsAutomatic commit
See also Standards and compatibilitySQL/2008 Vendor extension.
Transact-SQL The ALTER DATABASE statement is supported by Adaptive Server Enterprise. However, the statement's clauses supported by Adaptive Server Enterprise are disjoint from those clauses supported by SQL Anywhere.
ExampleThe following example disables jConnect support:
ALTER DATABASE UPGRADE JCONNECT OFF; |
The following example sets the transaction log file name associated with demo.db to mynewdemo.log:
ALTER DATABASE 'demo.db' ALTER LOG ON 'mynewdemo.log'; |
 |
Discuss this page in DocCommentXchange.
|
Copyright © 2012, iAnywhere Solutions, Inc. - SQL Anywhere 12.0.1 |